Snap switches



Dec. Z2, 1959 M. F. KOENIG 2,918,544

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INVENTOR.

Dec. 22, 1959 M. F. KOEN@ 9 2,918,544

SNAP SWITCHES Filed July 2, 1957 4SheetS-Sheet 2 m 2o\\ 4.9 4.a 99 99 2.o IT 4 5 l l W M j 3 IENTOR.

M. F. KOENIG SNAP SWITCHES Dec. 22, 1959 4 Sheets-Sheet 5 Filed July 2, 1957 8 INVENTOR Ma/'zz/z HKM/2l] BY iwf/im F e. \o

M. F. KoENlG 2,918,544

SNAP SWITCHES 4 ,sheetssheet 4 i Vil I l l l INVENTOR. F 4 ifa/'Z772 E /ae/z/ Dec. 22, 1959 Filed July 2. 1957 SNAP SWITCHES Martin F. Koenig, Milwaukee, Wis., assignor to Cutler- Hammer, Inc., Milwaukee, Wis., a corporation of Delaware Application July 2, 1957, Serial'No. 669,505

3 Claims. (Cl. 200-76) This invention relates to improvements in oscillating snap switches.

In snap switches of this type in addition to responsiveness and high speed operation it is also essential that the switch have an extremely high mechanical and electrical life. It is also advantageous to maintain pressure on the closed contact circuit until tripping is completed to eliminate creep and momentary zero contact pressure.` A further desirable feature is the prevention of contact freezing.

It is, therefore, an object of this invention to provide a snap switch having these advantages.

Another object of `this invention is to provide a snap switch of this type which is compact and rugged in construction, of simple design readily manufactured and assembled at low cost and positive and reliable in operation.

These objects are obtained by utilizing a contactor assembly which is loosely guided by an actuator plate so as to have free movement between its two limiting positions. A pair of opposed coiled compression springs act between the actuator plate and the contact carrier to floatably mount such contact carrier with respect to such actuator plate. The coiled compression springs operatively engage the actuator plate and contact carrier through spring pivots which consist of knife edges and spring guides seated thereon. The knife edges and spring guides have sufficient bearing length to resist relative rotation therebetween. Hence, the springs function to resiliently maintain the contact carrier in properly aligned position and yet permit it sufficient rocking movement to accomplish a self-alignment between the contacts carried by it and the fixed contacts. By such use of such coiled compression springs the snap switch has an extremely high mechanical life. Since such coiled compression springs can be easily held to close manufacturing tolerances for working loads between initial and nal working lengths, the snap switch is positive and reliable in operation.

In order to prevent momentary zero contact pressure and to provide a wiping contact thus preventing contact freezing and provide self-cleaning of contact surface, the contacts carried by the contact carrier are mounted on the outer ends of a leaf spring having its central portion secured to the contact carrier. This leaf spring is stressed in its outer limited position with respect to the contact carrier so as to have impressed force in this position. As the actuator plate moves the coiled compression springs toward dead center position, such leaf spring will move the contact carrier opposite to the movement of the actuator plate and hence force it through such dead center position while still maintaining good contact pressure. The movable contacts being on the ends of the leaf spring remote from its central attached portion, such contacts will travel through an arcuate path when the leaf spring is flexed from the outer limited position to the inner position flush with the contact carrier. This causes a relative I United States Patent-' 2,918,544 Patented' Dec." 22, 1959 ICC sliding movement between the fixed and movable contacts after the initial contact has been made, thus preventing freezing of such contacts.

For more detailed description of this invention reference is made to the following description of a specific embodiment read in connection with the accompanying drawings, in which:

Fig. 1 is a vertical sectional view of a snap switch constructed in accordance with this invention with the actuator plate raised;

Fig. 2 is a top plan view of such switch with part of the cover broken away and some parts shown in section;

Fig. 3 is a bottom plan view of such switch;

Fig. 4 is a sectional View taken on the line 4-4 of Fig. 1;

. Fig. 5 is a vertical sectional View similar to Fig. l with the actuator plate and contact carrier shown in the relative position assumed just after dead center position has been passed on the down stroke;

Fig. 6 is a vertical sectional view similar to Fig. 1 with the switch parts shown in the extreme position reached at the completion of a down stroke of the actuator;

Fig. 7 is an enlarged top plan view of the contactor assembly with a part broken away for clarity of illustration;

Fig. 8 is a View in side elevation of the contactor assembly of Fig. 7;

Fig. 9 is a view in end elevation of the contactor assembly `of Fig. 8;

Fig. 10 is an enlarged fragmentary sectional view taken on the line lil-10 of Fig. 7;

Fig. 11 is a top plan view of a modied form of contactor assembly;

Fig. l2 is a view in side elevation of the modified contactor assembly of Fig. 1l; and

Fig. 13 is a sectional view taken on the line 13-13 of Fig. 11.

This invention is shown embodied in a snap switch of an oscillating double snap type. Such switch comprises an open top base or housing 10 of insulating material in which the contact assemblies, contactor assembly, and actuator assembly is carried. The housing is enclosed by a cover 12 held in place by hollow rivets 14 which also provide openings for switch mounting devices. The base 10 has a central cylindrical well 16 providing operating space for the actuator return spring. Slots 18 extending from opposite sides of said well form a guide for the actuator plate. At opposite ends of the main chamber in the base are upper contact plate seats 20 and lower contact plate seats 22. The cover 12 may have a depending ange 24 iitting within the opening of the base to accurately locate the cover and make a good seal. A central opening in such cover reciprocally guides the actuator button.

In the embodiment shown, there are four fixed contact assemblies to provide two circuit operations one for out and one for in position. Each contact assembly includes a plate with attached contact element of identical design. The upper plates 26 for the `xed contacts have welded thereto a solid rivet 28 long enough to extend downward ly through the housing to the bottom thereof. The lower plates 3G for the fixed contacts have welded thereto a shorter solid rivet 32 which also projects through the bottom of the housing. Openings in the housing for the rivets 2S and the rivets 32 are offset to each side of the center line of the housing. However, the plates are angled inwardly toward the center of the housing so that the upper and lower buttons are in substantial alignment. On outside of the bottom of the housing short terminal plates and screws 34 are secured to diagonally opposite rivets 28 and 32, and long terminal plates and screws 36 are secured to the `other diagonally opposite rivets 28 and 32. The resultant offsetting of the terminal screws conserves width without minimizing the amount of insulation barrier positioned between such terminals.

The contactor assembly (see Figs. 7 to l() incl.) includesva contact carrier 38 having a central operating opening for the actuator assembly. n opposite sides of this opening, there are oppositely facing notches 4f) for loosely guiding the contact carrier by the actuator plate. Leaf-type spring contactors 42 with contact elements on the ends thereof are mounted on opposite sides of the contact carrier by rivets 44 passing through the central portion thereof. The contact carrier is provided with limit lugs 46 bent from` opposite ends thereof, each of which overlies an end of the contactor. The contactors 42 are made of bronze spring material and are stressed so that the ends are biased away from` the contact carrier into engagement with the lugs 46 with enough force to move the contactor 38 relative to `the actuator assembly, as hereinafter described. It has been found that the ends of the contactors 42 may have a movement of substantially .040 inch to .055 inch. Notches 47 in the ends of contact carrier 38 permit the spring contactors 42 to abut flush against the carrier 38 in the fully seated positions of the switch. At opposite ends of the opening in the contact carrier there are inwardly facing lugs provided with knife-like fulcrum edges 48 of substantial length, say about .085 inch to .O98 inch. This length has been found enough to prevent the relative rotational movement hereinafter explained.

The actuator assembly has an actuator plate 50 to the upper end of which is secured a button 52 slidably 0perable in the opening in the cover 12. The edges of such plate loosely slide in the slots 18 so that the actuator plate 50 has free oscillating movement within the housing. A compression spring 54 engages a lug 56 at the top of a notch 58 to resiliently force the actuator plate to the normal out or upper position. A pair of oppositely reacting spring pivots is formed by lugs struck out from the actuator plate and having knife edges 60 in substantially parallel alignment. These knife edges, like those on the contact carrier, have sufficient length to prevent the relative rotation hereinafter described. To simplify the making of the knife edges 60, the actuator plate 50 may be made of two identical plates each with struck out lug. These plates are then placed in back-to-back relationship and spot welded to form a single unit with oppositely facing knife edges in substantially parallel alignment.

A pair of oppositely reacting coiled compression springs 62 have tightly mounted on both ends thereof spring guides 64. These yspring guides have depressions with elongated V-shaped notches therein, into which'seat the knife edges 48 and 60 of the actuator plate and contact carrier. These notches are slightly longer than the knife edges 48 and 60 to provide for free oscillation of the guides 64 about the knife edges 48 and 60 while preventing relative rotation between such spring guides and such knife edges. Any axial rotation of the contact carrier 38 with respect to the actuator plate 50 can take place only through the flexing of the coiled compression springs 62. The coiled compression springs 62 are preferably made of music wire and are held within close specifications as to initial working load and final workA ing load and initial working length and final working length.k This insures that each spring will be uniform and thus continually floatably mount the contact carrier 38 relative to the actuator plate 50 so that there is only inconsequential friction, if any, between such actuator plate and the notches 4f) in the contact carrier. With the coil compression springs assembled as shown, the contact carrier 38 may be swung to normal position by rotatively adjusting the coiled springs 62 relative to the spring guides 64. Slight oscillation of the Contact carrier 38 to permit the contact elements to flatly seat on the fixed contact elements is permitted by the resilient torsional flexing of such springs. The life of the coiled compression springs is greater than that of the leaf springs usually employed in snap switches of this type. Such coiled compression springs may be held to close accuracy thus permitting the use of a free fioating contact carrier which has substantially no perceptible friction in the operation of the switch. This means that when dead center position is approached, only a little force is needed to overcome any frictional resistance tending to hold the mechanism at such dead center. Because of this it is possible to utilize the spring force in the spring contactors 42 to force the contact carrier 38 in the opposite direction from the movement of the actuator plate to swing the axis of the coiled springs through dead center while still maintaining positive contact pressure between the engaged contact elements. This relationship is shown by comparing Figs. l and 5. In Fig. 1 the lower spring contactor 42 has been forced flatly against the contact carrier 38. In Fig. 5 the contact carrier 38 is shown partly raised by the force of the lower spring contact 42 and dead center has been passed while still maintaining pressure at the contact elements. The down action has been completed and the engagement broken in the position shown in Fig. 6.

In the down position of the actuator 50 shown in Fig. 6 the upper contact elements are engaged and the circuit established. In the switch of this embodiment both pairs of terminals can be used for the establishing of circuits at both the `down and up position of the actuator. However, if only one pair of terminals is connected, then only one circuit is controlled. By selecting the desired pair, the single circuit may be established at either the down or up position. To economize on installations where only a single circuit need be controlled, one pair of contact assemblies may be removed and an assembly having a plate with offset portion and no contact element used. Such plain plate will furnish the abutting action essential to the operation of the switch. Also the spring contactor opposite such plain plate assembly may be left off. This saves four silver contact elements.

In the modification of the contactor assembly shown in Figs. l1 to 13, inclusive, the outer limit for the spring contactors 42 consists of brackets 66 and 68 mounted on opposite sides of a modified contact carrier 70. The ends of brackets 66 perform the same function as the lugs 46 of the contact carrier 38, previously described. The brackets 66 and 63 are secured by the same rivets 72 which also secure the spring contactors 42. To prevent the brackets 66 and 68 from swiveling about the rivets, the brackets 68 have upwardly projecting lugs 74 which abut against the inner edge of the opening in the contact carrier 70. The brackets 66 are provided with laterally extending fingers 76 which abut 'against the lugs 74 of the other bracket. Four brackets may be used as shown when a two-point abutment is needed. In some instances it may be satisfactory to use only one bracket 66 and one opposite bracket 68. If only one circuit is needed, only one spring contactor 40 and one or two brackets 68 on the same side need be used.

It will be apparent to those skilled in the art that various changes and modifications may be made to the embodiments herein `described without departing from the spirit of the invention or the scope of the appended claims.

I claim:

T. A snap action switch comprising a housing of insulating material having an actuator return spring well with sides slotted to form a guide for an actuator plate, a reciprocal actuator plate having its edges freely guided in said slots, a return spring in said well engaging said plate to resiliently force it to one position of travel, a pair of outwardly facing lugs formed out from opposite faces of said plate, said lugs having knife edges in substantial alinement and with sufficient length to prevent relative rotation of spring guides, xed contacts in said housing spaced from said opposite faces and alined with the path travelled by said lugs, a contact carrier operable in said housing and having a central opening through which said actuator plate passes, oppositely facing notches in the sides of said opening for loosely receiving the edges of said actuator plate for guiding said carrier, inwardly facing lugs on the opposite ends of said opening spaced from the lugs on said actuator plate, said inwardly facing lugs having knife edges in substantial alinement and with sufficient length to prevent relative rotation of spring guides, a pair of oppositely reacting coiled compression springs having tightly mounted spring guides on the ends thereof mounted between said inwardly and outwardly facing lugs, said spring guides having elongated V-shaped notches in which the knife edges of said lugs seat to prevent relative rotation between said coiled compression springs and said lugs whereby said springs hold said contact carrier against relative axial rotation with respect to said actuator plate except for permissible flexing of said springs for contact alinement, a leaf spring contactor with contacts on opposite ends thereof in alinement with said tixed contacts operable within said housing, said contactor having a central opening extending 4around the opening in said contact carrier, the central portions of said spring contactor being secured to the central portions of said contact carrier, said contactor being inherently stressed so that its ends are biased away from said contact carrier, positive engaging lugs acting between said contact carrier and said contactor to limit the movement of said contactor ends away from said contact carrier to maintain an inherent stressing at all times, and a cover for said housing having an opening for guiding said actuator plate.

2. In a snap action switch, in combination, an insulating housing, spaced stationary contacts mounted in said housing, a contact carrier extending between said stationary contacts and having an aperture therein, a leaf spring contactor having contacting elements on the ends thereof for engagement with said stationary contacts to bridge the latter, said leaf spring contactor being secured to said contact carrier and the ends of said leaf spring contactor being normally spaced from the plane of said contact carrier, an actuator positioned between said stationary contacts and extending through the aperture in said contact carrier and having a portion guided in said housing for reciprocal movement therein, said actuator having a pair of projecting pivot portions extending in opposite directions therefrom, said contact carrier having a pair of projecting pivot portions extending toward the respective pivot portions on said actuator and laterally spaced therefrom, a pair of helical compression springs each being positioned in compression between each actuator pivot portion and the respectively associated contact carrier pivot portion, retaining means embracing the ends lof said compression springs each having a cooperating portion substantially complemental to an associated projecting pivot portion for retaining said springs in compression between said projecting pivot portions and affording pivotal movement of the latter therein, means for limiting the movement of said contact carrier away from said stationary contacts so that movement of said actuator in one direction causes movement of said compression springs through dead center position to snap said contacting elements into engagement with said stationary contacts and to bias the ends of said leaf spring contactor toward said contact carrier, the ends of said leaf spring contactor having sufficient bias to maintain engagement of the contacts and to move said contact carrier toward and through said dead center position as said actuator is operated to move said compression springs toward dead center position from the opposite direction.

3. In a Snap action switch, in combination, an insulating housing, spaced stationary contacts mounted in said housing, a contact carrier extending between said stationary contacts and having an aperture therein, a leaf spring contactor having contacting elements on the ends thereof for engagement with said stationary contacts to bridge the latter, said leaf spring contactor being secured to said contact carrier and the ends of said leaf spring contactor being normally spaced from said contact carrier, an actuator positioned between said stationary contacts and extending through the aperture in said contact carrier and having a portion guided in said housing for reciprocal movement therein, said actuator having a pair of pivot portions extending in opposite directions therefrom, said contact carrier having a pair of pivot portions extending toward the respective pivot portions on said actuator, a pair of helical compression springs each being positioned in compression between each actuator pivot portion and the respectively associated Contact carrier pivot portion, said pivot portions of said actuator and said pivot portions of said Contact carrier having knife edges on their free ends, a cup-shaped guide member inserted on each end of each said compression spring, the bottom of each said cup-shaped guide member having a depression for receiving the knife edge end of the respective pivot portion to retain the springs in compression between the respective pivot portions of the actuator and contact carrier, said knife edge ends having suicient width to prevent relative rotation between said compression springs and said pivot portions whereby said springs maintain said contact carrier against relative axial rotation with respect to said actuator except for permissible iexing of said springs for contact alinement, means for limiting the movement of said contact carrier away from said stationary contacts so that movement of said actuator in one direction causes movement of said compression springs through dead center position to snap said contacting elements into engagement with said stationary contacts and to bias the ends of said leaf spring contactor toward said contact carrier, the ends of said leaf spring contactor having sufficient bias to maintain engagement of the contacts and to move said contact carrier toward and through said dead center position as said actuator is operated to move said compression springs toward dead center position from the opposite direction.

References Cited in the tile of this patent UNITED STATES PATENTS 887,252 Jackson May 12, 1908 1,256,332 Krantz Feb. l2, 1918 1,861,641 Nicholson June 7, 1932 2,532,468 Sweger Dec. 5, 1950 2,565,350 Burns Aug. 21, 1951 2,653,198 Krenke Sept. 22, 1953 2,750,463 Roeser June 12, 1956 FOREIGN PATENTS 189,857 Great Britain Dec. 4, 1922 546,135 Great Britain June 29, 1942 730,991 Great Britain June 1, 1955 `714,021. Germany Nov. 20, 1941 

